1. Field of the Invention
The present invention relates to color conversion definition creating method and color conversion definition creating apparatus for creating a color conversion definition converting coordinate points within a color reproduction area of a device (for example, a printer) mediating between an image and image data in a three-dimensional color space (an RGB color space) taking as axes R (red), G (green) and B (blue), depending on the device, into coordinate points within a color reproduction area of printing in a four-dimensional color space (a CMYK color space) taking as axes C (cyan), M (magenta), Y (yellow) and K (black) for printing, and a color conversion definition creating program storage medium storing a color conversion definition creating program which causes a computer to operate as the color conversion definition creating apparatus when the color conversion definition creating program is incorporated into the computer.
2. Description of the Related Art
Hitherto, as an apparatus for applying a high quality of color processing for printing to image data representative of an image, there is known an apparatus (for example, U.S. Pat. No. 6,002,806) in which upon receipt of CMY data representative of a combination (coordinate points within a CMY color space) of density values of C, M and Y, CMYK data representative of a combination (coordinate points within a CMYK color space) of dot % of C, M, Y, and K is outputted.
This apparatus receives the CMY data and performs a color processing. Even recently, while there are proposed various improvements on such an apparatus, such an apparatus is concerned with a well-established technology in base, and there exist many skilled persons capable of operating such an apparatus to perform a high quality of color processing (this color processing is referred to “set up”).
Recently, as color management technologies have come into wide use, there is increased a necessity for obtaining a high quality of CMYK data for printing in accordance with color data other than the CMY data. As one of the examples, it may be required that upon receipt of RGB data representative of a combination (coordinate points within a RGB color space) of values of R, G, and B, an image, in which a color of a printed image obtained through an output of a printer based on the RGB data is faithfully reproduced, is printed.
When the RGB data is converted into the CMYK data, not only it is necessary to convert the RGB data into the CMYK data capable of obtaining the same color as the colorimetric value, but also it is necessary to convert the RGB data into the CMYK data excellent in printability. A large factor as to whether there is the printability is a value of K. And when the RGB data is converted into the CMYK data capable of obtaining the same color as the colorimetric value, there is a need to determine the value of K in accordance with a printing company, a printing machine and the like.
Even if the use of various techniques makes it possible that the RGB data is converted into the CMYK data excellent in printability and capable of obtaining the same color as the colorimetric value, matching of a color of an image outputted from a specified printer in accordance with the RGB data to a color of an image reproduced in printing is concerned with only areas wherein a color reproduction area of the printer overlaps with a color reproduction area of printing. In the event that a color reproduction area (an outline of a printer profile) of the printer is greatly different from a color reproduction area (an outline of a printing profile) of printing (usually, the outline of the printing profile is narrower), this involves a problem as to how a portion exceeding out of the color reproduction area of printing, of the color reproduction area of the printer is converted into the color reproduction area of printing (this is referred to as a gamut mapping) so that an image, which has a color very approximating the color of the image outputted from the printer in accordance with the RGB data and involves no feeling of wrongness in a color tone, is reproduced by a printing